It is well known that lubricating oils used in internal combustion engines lose their effectiveness over a period of time due to accumulation of dirt or other foreign matter therein and due to breakdown of the oil or the additives incorporated therein. In order to prevent excessive engine wear, it is therefore necessary to change the oil at periodic intervals. Typically, the oil is removed from the engine by withdrawing a plug from the oil pan at the bottom of the engine and allowing the oil to run out into some kind of collector. The conventional procedure, however, is disadvantageous in that it is necessary either to have a lift to raise the car above the ground, or to crawl under the car. Not infrequently, the person changing the oil gets all dirty. Also, oil is often spilled, which leaves unsightly stains and pollutes the environment.
For maximum efficiency, it is most desirable that the engine oil be changed while hot. In actual practice, however, the vehicle is usually allowed to sit before the oil is drained therefrom in the conventional fashion. This arises both from the necessity of waiting one's turn to receive service at a service station and also from a desire of a person changing the oil not to be burned with hot oil as he removes the plug from the drain outlet of the oil pan.
Various types of alternative systems have been proposed to avoid draining the oil in the conventional fashion. One system now being marketed involves a pump designed to be driven by a conventional electric hand drill. The suction line of the pump is inserted down the oil dipstick tube and the delivery line is inserted in a suitable container. This system is not satisfactory, however, because it lacks sufficient power to remove the heavy sludge which accumulates at the bottom of the oil pan.
Another system is disclosed in Boyd, et al., U.S. Pat. No. 3,773,091. In this system, a vacuum tank is evacuated by connecting it to the intake manifold of an internal combustion engine. When the pressure in the tank has been reduced to the desired level, the vacuum line is closed off, and a suction line communicating between the drain opening of the oil pan and the tank is opened. Ambient pressure then forces the oil from the drain pan through the line into the evacuated tank. This system is not entirely practical because it requires a permanent connection to the drain opening of the engine oil pan.
A similar system is disclosed in Winkelvoss, U.S. Pat. No. 4,119,117 in which a vacuum tank is connected to the crankcase of an internal combustion engine through a specially designed control valve which shuts off the suction line after all of the oil has been withdrawn. The valve arrangement of Winkelvoss is complex and expensive.
A further problem has arisen in connection with the probe itself, relating to the fact that the probe is somewhat delicate, and can be damaged if it is pinched or bent during normal use, transportation, etc. of the apparatus.